The conventional ink pens, such like markers or highlighters, are generally used for marking, so their nibs must be thicker. Therefore, lots of them only have the ink cotton tube for each with single color.
However, the pen with single color for marking is dull and hard to exactly show where the marks are. To resolve it, the user must buy many pens with different colors. For consumers, they waste additional cost and are hard to carry.
The above mentioned colored ink pen limited by the thicker nib is not able to use many press lock structures to perform many cartridges and ink cotton tubes with different colors. Therefore, in the market, many colored ink pens are arranged two cartridges and two ink cotton tubes with two different colors which are respectively arranged at two ends of the pen shaft. When the user is using, the caps respectively covered at the two ends of the pen shaft must be opened (or separated from the corresponding end of the pen shaft) and the two different colors may be used by changing two ends of the pen shaft in turn.
In addition, the nib of the conventional ink pen is directly connected to the ink cotton tubes that the nib may be deformed or broken by overpressing or incorrect writing posture after a long time.
In view of the foregoing circumstances, the inventor has invested a lot of time to study the relevant knowledge, compare the pros and cons, research and develop related products. After quite many expetireents and tests, the “multi-function writing implement” of this invention is eventually launched to improve the foregoing shortcomings, to meet the public use.